Cover for truck beds

ABSTRACT

A cover for truck beds consisting of a flexible cover sheet wound on a reel mounted at the forward end of the truck bed and extendable rearwardly from said reel to cover said truck bed, a reversible power mechanism for turning said reel to selectively pay out or reel in the cover sheet, a tension mechanism operable to apply an increasing tension to said cover sheet as it is paid out from the reel, and a latch mechanism operable to secure the cover sheet in its extended position independently of the tension mechanism.

United States Patent [#51 Unruh V in] 3,759,568 Sept. 18, 1973 1 covEnnon TRUCK maps [76] Inventor:

Park, Kans. 66212 I 221 Filed: Sept. 28, 1911 [21] Appl.No.:184,568

, 52 1 'u.s ."c| ssassins/s71,160/315,

' v 296/100 [51] Int. Cl B603 7/08 [58] Field oi'Search 296/98, 100;

105/377'; 254/178, 188, 173, 173 R, 173 A, 173 B; 160/235, 265, 266,268, 310, 315;

[56] References Cited UNITED STATES PATENTS 1,649,797 11/1927 Winn, Jr.160/310 X 2,454,365 11/1948 Woolery 254/178 X 2,898,147 8/1959 Hornet296/98 Cecil Unruh, 8603 Floyd, Overland 2,958,083 11/1960 Shook et al160/238 3,472,548 10/1969 Comisac ..296/98X 3,086,811 4/1963 Hartviksen296/98 Primary Examiner-Leo Friaglia Assistant ExaminerDavid M. MitchellAttorney-John A. Hamilton [57] ABSTRACT A cover for truck bedsconsisting of a flexible cover sheet wound on a reel mounted at theforward end of the truck bed and extendable rearwardly from said reel to.cover said truck bed, a reversible power mechanism for turning saidreel to selectively pay out or reel in the cover sheet, a tensionmechanism operable to apply an increasing tension to said cover sheet asit is paid out from the reel, and a latch mechanism'operable to securethe cover sheet in its extended position independently of the tensionmechanism.

5 Claims, 7 Drawing Figures PATENTEU SEP 1 8 I975 sum 1 or 2 INVENTOR.fleci/ Unruh BY A fro/we y.

PAIENTEDSEPI ems 3759568 sum 2 or 2 A A-f" "-1 INVENTOR. Cad/7 UnruhArm/we y.

COVER FOR TRUCK BEDS This invention relates to new and usefulimprovements in covers for truck beds, and has particular reference to atruck bed cover especially adapted for use in connection with dumptrucks and the like when hauling sand, gravel, grain, and other granularor powdered material. Material blowing from uncovered loads of suchmaterial, due to the wind created by motion of the truck, is acontinuing source of annoyance and even danger to following motorists,sometimes causing damage to automobile finishes, distracting drivers,and get ting in their eyes. Many states have already prohibited by lawthe hauling of such materials in open-bed, uncovered trucks, as a safetyprovision.

Accordingly, the principal object of the present invention is theprovision of a truck bed cover which may be applied easily andconveniently to pre-existing truck beds, and which effectively coversthe bed to prevent blowing of the load material therefrom. To this end,the cover consists of a flexible coversheet wound on a reel mountedrotatably at the forward end of the truck bed and extendable rearwardlytherefrom to cover the truck bed, and means for turning said drum reelto pay out or reel in said cover sheet.

Another object is the provision of a truck bed cover of the characterdescribed having tensioning means operable to apply tension to saidcover sheet in an increasing degree as it is paid out from said reel,whereby said cover sheet is maintained smoothly taut and will not flapor billow in the wind.

A further object is the provision of a truck bed cover of the characterdescribed wherein said tensioning means is resiliently yieldable, andwith the addition of latch means operable to lock said cover sheetpositively in its fully extended position, whereby said coverv sheet isprevented from billowing or flapping as a result of yielding of saidtensioning means.

A still further object is the provision of a truck bed cover of thecharacter described which is fully powered and may be operated from anyconvenient remote station, such as the truck cab.

Other objects are simplicity and economy of construction, and efficiencyand dependability of opera-.

' truck bed, showing a cover embodying the present invention appliedoperatively thereto,

FIG. 2 is a top plan view partially broken away and foreshortened, ofthe device as shown in FIG. 1,

FIG. 3 is an enlarged, fragmentary sectional view taken on line III-IIIof FIG. 2, with parts left in elevation and partially broken away, andshowing the cover latch engaged,

FIG. 4 is a view similar to FIG. 3, but showing the cover latchreleased,

FIG. 5 is a fragmentary sectional view taken on line V-V of FIG. 3, withparts left in elevation,

FIG. 6 is an enlarged, fragmentary sectional view taken on line VIVI ofFIG. 2, and

FIG. 7 is a schematic wiring diagram of the electrical control system.

Like reference numerals apply to similar parts throughout the severalviews, and the numeral 2 applies generally to-a truck bed, the specificconstruction of which is not pertinent to the present invention exceptthat it be open at'the top. As shown, it is a dump truck bed having sidewalls 4, usually a rear dump gate (not shown), and a front wall 6 (seeFIG. 6) extending upwardly above said side walls, then angled forwardlyto form a pan 8 which overhangs and protects the truck cab (not shown),said pan having an upright lip 10 at its forward edge. Most commonly,side walls 4 are provided with upward extensions 12 to the full heightof the front wall, to increase the capacity of the bed.

A shaft 14 forming a reel for a flexible cover sheet 16 extendshorizontally and transversely just forwardly of pan lip 10, beingjournalled in bearings 18 (see FIG. 2) carried by arms 20 affixed to andextending forwardly from side wall extensions 12 at each side of thetruck bed. One end of cover sheet 16 is affixed to shaft 14, and thecover sheet is reeled thereon, but may be unreeled therefrom by rotationof said shaft to extend rearwardly over and completely cover the truckbed. Said cover sheet is of course wide enough to completely bridge thelateral distance between the bed side walls, and may be formed of canvasor any other suitably flexible material, waterproofed if desired.

The rearward end of cover sheet 16 is affixed to a carriage indicatedgenerally by the numeral 22, and carried for forward and rearwardmovement by a pair of channel iron tracks 24 affixed respectively to theouter surfaces of side wall extensions .12 adjacent the upper edgesthereof, and extending substantially the full length of the truck bed.Said tracks are parallel, and are preferably inclined slightlydownwardly toward their rearward ends, for a reason which will presentlyappear. Carriage 22 includes a pair of trucks each consisting of avertical plate 26 arranged adjacent the associated track 24, a pair ofspaced apart rollers 28 carried rotatably by said plate and engagedoperatively in the associated track, and. a bridge member 30 extendingtransversely across the truck bed, above the side walls, with its endportions extending downwardly and welded or otherwise rigidly affixed tothe respective plates 26. Bridge member 30 may be arched as shown foradditional strength, and the rearward edge of cover sheet 16 is affixedthereto as by rivets 32.

Affixed to each extended end of shaft 14 is a cable drum 34, the outerend wall of which constitutes a sprocket wheel 36. Each of said sprocketwheels is operatively connected by means of sprocket chain 38 with asprocket wheel 40, sprocket wheels 40 being affixed respectively on theopposite ends of a drive shaft 42 extending horizontally andtransversely just forwardly of front bed wall 6, and journalled inbearings, not shown, mounted on gusset plates 44 forming portions of thetruck bed. Said drive shaft is rotated, selectively in either direction,by a reversible electric motor 46, through a geared speed reducer 48,said motor and speed reducer being mounted beneath pan 8 by bracket 50,as best shown in FIG. 6. It will be understood that speed reducer 48 isof a self-locking type, that is, that the motor cannot be turned by anydegree of torque applied to drive shaft 42. For this purpose, thereducer may include a worm driven by motor 46 and engaging a worm gearfixed on the drive shaft.

A flexible steel cable 52 is disposed at each'side of the truck bed. Oneend of each cable is affixed to and wound on the cable drum 34 at thatside of the truck bed. As best shown in FIG. 1, each cable extendsrearwardly from its drum and is trained around a pulley 54 carriedrotatably by a bracket 56 affixed to the extreme rearward end of thetruck bed, then forwardly and trained about a free pulley 58 carriedrotatably by a clevis 60 intermediate the forward and rearward ends ofthe truck bed, then rearwardly and trained about a second pulley 62carried rotatably by bracket 56, and finally forwardly and secured tothe associated truck plate 26, as at 64. The rearward end of a helicaltension spring 66 is affixed to clevis 60, and the forward end of saidspring is attached, as at 68, to the associated side wall extension 12,whereby to maintain the cable under tension. Cables 52 are wound ondrums 34 oppositely to the direction of winding of coversheet 16 on reel14, so that the cover sheet is wound onto the reel as cable is paid outfrom the drums, and vice versa. Also, the drums 34 are of a diameter atleast slightly larger than the maximum diameter of the cover sheet onreel 14, so that the cable is always reeled in, or paid out, at greaterlinear rates than the cover sheet is correspondingly paid out or reeledin.

There is also included a latch mechanism indicated generally by thenumeral 70, and best shown in FIGS. 3-5, for securing carriage 22releasably in position with cover sheet 16 fully extended to cover thetruck bed. While it could take many forms, as shown it comprises, inconnection with each track 24, a U-shaped latch lever 72 which opensupwardly, and extends upwardly into the associated track 24 through aslot 74 formed in the bottom wall of said track. Said lever is pivotedto said track on a horizontal transverse axis beneath the level ofrollers 28, as at 76. The lower end of lever 72 forms a latch pawl 78.Thus as carriage 22 approaches the rearward limit of its travel, therearmost roller 28 of each carriage truck engages in lever 72 and pivotsit rearwardly, moving pawl 78 into locking engagement with a notchedkeeper 80 fixed to the end of a slide bar 82 movable in a bearing member84 fixed to side wall 12. The slide bar and keeper are biased toward aposition to engage the pawl by means ofa spring 86 carried on the bar,its movement in this direction being limited by a collar 88 fixed onsaid bar. Keeper 82 may be retracted against spring 86, whereby torelease the pawl, by a solenoid coil 90 also mounted on side wall 12,bar 82 projecting into and forming an armature for the solenoid coil,whenever electric current is supplied to said coil.

Affixed to one of truck plates 26 is a depending switch operating finger92. When the cover sheet is fully extended to cover the truck bed, saidfinger engages and depresses the operating plunger 94 of a limit switch96 also mounted on side wall 12. As diagrammed in FIG. 7, switch 96includes a pair of normally closed contacts 98 and 100 adapted to beopened by depression of plunger 94. When cover sheet 16 is fullyretracted to uncover the truck bed, finger 92 engages and depresses theoperating plunger 102 of a second limit switch 104 also mounted on sidewall 12, and including a pair of normally closedcontacts 106 and 108adapted to be opened by depression of plunger 102. The control systemalso includes a source of electric power which may be the truck battery110, a normally open pushbutton switch 112, a pushbutton switch 114having a pair of normally open contacts 116 and 118, and a relay 120having an armature 122 which is normally open, but which is closableselectively on fixed contacts 124 and I26 by energization of relay coils128 and 130 respectively.

In operation, assuming that the cover sheet has been fully extended tocover the truck bed, and carriage 22 locked in its rearwardmost positionby latches 70, as shown in FIGS. 1-3, the operator retracts the cover bymomentarily depressing pushbutton 114. The closure of contact 116completes a circuit to solenoids 90, releasing the latches to freecarriage 22 for forward movement, and the closure of contact 118completes a circuit to relay coil 128 to close said relay on contact124, but this at first has no effect since contact of switch 96 is thenopen. Closure of switch contact 118, however, also closes a circuitby-passing contacts 100 and 108, through wires 132 to motor 46,energizing said motor to turn shaft 14 in a clockwise direction, asviewed in FIG. 1, whereby to reel the cover sheet onto said shaft, andto pay out cables 52 from drums 34. As soon as carriage 22 has movedforwardly enough to allow closure of contact 100, and to clear latches70, pushbutton 114 may be released. Contact 100 then maintains the motorcircuit through contact 108 (then closed), and also a holding circuitthrough wire 134, for relay coil 128, so that retraction of the coversheet continues. Contacts 98 and 106 of the limit switches, thoughclosed, have no effect at this time since they derive current only frompushbutton 112 or relay contact 126, both of which are open. A suitablemechanical interlock may be provided between pushbuttons I12 and 114, toprevent accidental simultaneous closure of both.

During retraction of the cover, cables 52 are of course paid out fromdrums 34 more rapidly than the cover sheet 16 is wound on reel shaft 14,due to the larger diameters of drums 34, but the cables and the coversheet are maintained taut by the resilient recovery of springs 66, sothat said cover sheet winds smoothly onto shaft 14. When the cover sheetis fully retracted to uncover the truck bed, finger 92 engages and openslimit switch 104, opening of contact 108 of said switch interruptingboth the operative circuit of the motor, and the holding circuit ofrelay coil 124, so that relay opens and the entire system is at rest.

Similarly, when it is desired to extend the cover sheet, the operatorpresses pushbutton 112, completing a circuit to coil to close relay 120on contact 126, and to complete a by-pass circuit through wire 136bypassing limit switch contact 106 (then open) and limit switch contact98 (then closed) to motor 46 through wire 138 whereby to cause operationof said motor to turn reel shaft 14 to pay out cover sheet 16, and drums34 to reel in cables 52. When limit switch 104 closes, pushbutton 112may be released, the motor circuit being maintained through contacts 106and 98 (then both closed), and a holding circuit for relay coil 130being established through wire 136, so that extension of the cover sheetcontinues until finger 92 opens limit switch 96 to return the system torest as before. As the cover sheet is extended, more cable is reeled inthan cover sheet is paid out, due to the larger diameters of cable drums34 as compared to reel shaft 14, so that springs 66 are graduallyextended to apply a greater and greater tension to the cover sheet. Thefarther said cover sheet is extended, the greater the tension thereofmust be to prevent it from billowing and flapping in the wind, andsprings 66 are selected to supply this tension at the properlyincreasing rate. The downward and rearward slope of tracks 24 providesthat the cover sheet, while initially held well above side walls 12 toprevent abrading friction therebetween, is gradually lowered closer andcloser to said side walls to provide better wind seal. Actually, whileshown as stretched straight, the cover sheet usually sags somewhat toactually engage said side walls.

When the cover sheet is fully extended, carriage 22 is engaged andlocked in position by latch mechanisms 70, automatically. These latchmechanisms are desirable since, in their absence, the wind could stillget under the cover sheet and cause upward billowing thereof, especiallyat higher tr-uck speeds, and said billowing could occur since forwardmovement of carriage 22 could still be permitted by further oscillatingyielding of springs 66. Thus, latch mechanisms 70, by positivelypreventing forward movement of the carriage, eliminate or at leastgreatly reduce any possible billowing and flapping of the cover sheet.

To permit stoppage of cover sheet 16 at any intermediate position in itsmovement, for example in an emergency, or when it might be desired tocover only a portion of the truck bed, normally open relays 140 and 142are inserted respectively in holding circuit wires 134 and 136, as shownin FIG. 7. Said relays are closable by energization of their respectivecoils 144 and 146, and are latched closed by a latch mechanism 148common to both. Said latch mechanism may be released to open both ofrelays 140 and 142 by pressing a single stop button 150. Coil 144 iswired to receive current whenever pushbutton 114 is pressed, and coil146 to receive current whenever pushbutton 112 is pressed. Thuswhenever, while cover sheet 16 is being moved in either direction, andis at any position, it'may be stopped by pressing button 150. This opensboth of relays 140 and 142, of course including the one operative atthat time. This interrupts the holding circuit of the coil 128 or 130 ofrelay 120-which is then operative, allowing relay 120 to open tointerrupt the operative motor circuit. The system is then at rest, withcover sheet 16 extended to whatever degree it was when button 150 waspresed, and will remain at rest when button 150 is released. Motor 46may be restarted, to either further ex tend or further retract the coversheet, as may be desired, by pressing the appropriate pushbutton 112 or114 momentarily. This energizes the desired relay coil 144 or 146 toclose the associated relay 140 or 142,

which is then secured closed by latch mechanism 148. This in turncompletes the holding circuit to the desired coil 128 or 130 of relay120, causing relay 120 to complete the desired motor circuit. All of thecontacts of limit switches 96 and 104 are of course closed at thistime.- At this point, one of relays 140 or 142 is still open but it willbe closed automatically whenever the corresponding pushbutton 112 or 114is next pressed to initiate movement of the cover sheet in the oppositedirection. In normal operation, when it is desired only to cover oruncover the truck bed completely, relays 140 and 142 remain closed atall times.

While l have shown and described-a specific embodiment of my invention,it will be readily apparent that many minor changes of structure andoperation could be made without departing from the spirit of theinvention.

What I claim as new and desire to protect by Letters Patent is: a

1. A cover for an open-topped truck bed having side I walls, said covercomprising:

a. a pair of track members affixed to said truck bed side walls adajcenttheir upper edges and extending substantially the full length thereof,

b. a carriage carried by said tracks for movement therealo'ng andincluding a bridge member extending transversely across the top of saidtruck bed,

c. a pulley mounted rotatably at the rearward end of said truck bed,

d. a cover sheet reel mounted rotatably at the forward end of said truckbed on a horizontal transverse axis,

e. a pliably flexible cover sheet wound on said reel extendingrearwardly therefrom, and secured at its rearward edge to said bridgemember,

f. a cable drum affixed coaxially to and rotatable with said cover sheetreel, I

g. a flexible cable wound on said drum oppositely to the winding of saidcover sheet on said reel and extending rearwardly from said drum aroundsaid pulley, then forwardly and affixed to said carriage,

h. reversible power means for rotating said reel and drum selectively ineither direction, whereby said cover sheet is reeled in and said cableis simultaneously paid out or vice versa, said power means beingself-locking in the sense that said reel and drum cannot be turned byany amount of torque applied thereto by tension in said cover sheet orsaid cable, said cable drum being of larger diameter than the maximumdiameter of the cover sheet roll on said reel, whereby said cable isalways paid out from or wound onto said drum at a greater linear ratethan said cover sheet is respectively wound onto or pair out from saidreel, and

i. tensioning means operable to take up any slack developing in saidcable, whereby to maintain tension in said cover sheet.

2. The device as recited in claim 1 wherein said cable tensioning meansis operable to apply tension to said cover sheet in a graduallyincreasing degree as said cover sheet is extended from said reel.

3. The device as recited in claim 1 with the addition of a second pulleycarried rotatably at the rearward end of said truck bed, and a movablethird pulley disposed intermediate the forward and rearward ends of saidtruck bed, said cable extending rearwardly from said drum and beingtrained about said second pulley, then forwardly and trained around saidthird pulley, then rearwardly and trained around said first-namedpulley, then forwardly for attachment to said carriage, and wherein saidtensioning means comprises a forwardly and rearwardly extending tensionspring secured at its rearward end to said third pulley and at itsforward end to said truck bed, whereby said spring applies a graduallyincreasing tension to said cover sheet as said cover sheet is extendedfrom said reel.

4. The device as recited in claim 1 with the addition of a latchmechanism carried by said tracks and operable to lock said carriagereleasably in its rearwardmost position with said cover sheet fullyextended to cover means.

:0: a a a a

1. A cover for an open-topped truck bed having side walls, said covercomprising: a. a pair of track members affixed to said truck bed sidewalls adajcent their upper edges and extending substantially the fulllength thereof, b. a carriage carried by said tracks for movementtherealong and including a bridge member extending transversely acrossthe top of said truck bed, c. a pulley mounted rotatably at the rearwardend of said truck bed, d. a cover sheet reel mounted rotatably at theforward end of said truck bed on a horizontal transverse axis, e. apliably flexible cover sheet wound on said reel extending rearwardlytherefrom, and secured at its rearward edge to said bridge member, f. acable drum affixed coaxially to and rotatable with said cover sheetreel, g. a flexible cable wound on said drum oppositely to the windingof said cover sheet on said reel and extending rearwardly from said drumaround said pulley, then forwardly and affixed to said carriage, h.reversible power means for rotating said reel and drum selectively ineither direction, whereby said cover sheet is reeled in and said cableis simultaneously paid out or vice versa, said power means beingself-locking in the sense that said reel and drum cannot be turned byany amount of torque applied thereto by tension in said cover sheet orsaid cable, said cable drum being of larger diameter than the maximumdiameter of the cover sheet roll on said reel, whereby said cable isalwayS paid out from or wound onto said drum at a greater linear ratethan said cover sheet is respectively wound onto or pair out from saidreel, and i. tensioning means operable to take up any slack developingin said cable, whereby to maintain tension in said cover sheet.
 2. Thedevice as recited in claim 1 wherein said cable tensioning means isoperable to apply tension to said cover sheet in a gradually increasingdegree as said cover sheet is extended from said reel.
 3. The device asrecited in claim 1 with the addition of a second pulley carriedrotatably at the rearward end of said truck bed, and a movable thirdpulley disposed intermediate the forward and rearward ends of said truckbed, said cable extending rearwardly from said drum and being trainedabout said second pulley, then forwardly and trained around said thirdpulley, then rearwardly and trained around said first-named pulley, thenforwardly for attachment to said carriage, and wherein said tensioningmeans comprises a forwardly and rearwardly extending tension springsecured at its rearward end to said third pulley and at its forward endto said truck bed, whereby said spring applies a gradually increasingtension to said cover sheet as said cover sheet is extended from saidreel.
 4. The device as recited in claim 1 with the addition of a latchmechanism carried by said tracks and operable to lock said carriagereleasably in its rearwardmost position with said cover sheet fullyextended to cover said truck bed.
 5. The device as recited in claim 4wherein said latch mechanism is provided with spring engaging meansoperable automatically as said carriage reaches its rearwardmostposition, and manually actuated release means.